Results of the 1st to the 4th Proficiency Testing on Food Analysis

The Japan Society for Analytical Chemistry has carried out proficiency testing on food analysis four times from 2004 to 2008 following the procedure specified in ISO/IEC GUIDE 43-1. The test sample was different in each test: powdered milk for 1st, fish sausage for 2nd, pudding for 3rd and baby food for 4th. The constituents to be analyzed were common for each test; they were protein, lipid, ash, water, calcium, iron, sodium and phosphorus. The number of laboratories that participated was 65 at the most (3rd), and 53 at least (4th). The analytical methods applied in the testing were the Japanese official method concerning food analyses. In the test, samples were distributed to laboratories after being tested concerning homogeneity, and analytical reports from laboratories were evaluated using z scores of the robust method. The ratios of laboratories evaluated as being satisfactory, or | z | <= 2, were 79 similar to 91% in 1st PT, 76 similar to 96% in 2nd PT, 74 similar to 90% in 3rd PT and 83 similar to 86% in 4th PT, depending on the constituents.